Mobile phones are attempted to be made as small as possible in order to make them easily transportable in pockets or handbags. This tendency is, however, controversial to the feasibility of the telephone; because the user interface, i.e. mainly the keyboard and the display, must be made so small that on the display screen, there is room for limited information only (or the information must be shown on the screen with unreasonably small characters), and the keys and the spaces between them are unreasonably small for the fingers of an adult user. As a solution, there are suggested various folding telephones.
FIGS. 1-4 illustrate various prior art solutions designed mainly in order to enlarge the user interface of a small-size telephone. The mobile phone 100 illustrated in FIG. 1 comprises a housing 101 and a turning arm 102 attached to the side of the housing by means of a rotating joint. The loudspeaker 103 is provided in the housing 101, and the microphone 104 is located at the end of the turning arm 102. In preparation for use, the turning arm 102 is turned to a position illustrated by a uniform line in the drawing, and during transport it is turned to a position at the side of the housing 101, illustrated by a dotted line. The mobile phone 200 illustrated in FIG. 2 comprises a housing 201 and a flap 202 attached by a hinge at the bottom edge of the housing. In the transport position, the flap 202 covers the keyboard 203, and in preparation for use, the flap 202 is turned to the position illustrated in FIG. 2, so that the microphone 204 provided at the outer end of said flap 202 comes near to the user's mouth in the regular usage position. The regular usage position means that the user holds the telephone in his hand, so that the loudspeaker 205 is pressed against his ear and the flap 202 points more or less towards his chin.
FIG. 3 illustrates a mobile phone 300 provided with a sliding lid, said mobile phone 300 comprising a housing 301 and a lid 302 attached thereto by means of slide rails. In the transport position, the lid 302 completely covers the keyboard 303. The usage position can be chosen according to how large a part of the keys 303 the user needs. FIG. 3 illustrates a usage position where the lid 302 is completely open. The microphone 304 is located in the bottom part of the lid 302, and the loudspeaker 305 is located in the top part of the housing 301. The curved shape of the telephone 300 helps to find a comfortable usage position where the microphone 304 and the loudspeaker 305 are placed in a desired position with respect to the user's mouth and ear. The mobile phone illustrated in FIG. 3 can be called a telescopic telephone, because its length in the direction of a given (curved) dimension can be adjusted by sliding two mutually attached elements in relation to each other in the direction of said dimension.
In the applications illustrated in FIGS. 1-3, the folding or sliding features of the telephone do not solve the problem connected to the size of the keyboard and display, but the emphasis has been to adjust the distance between the microphone and the loudspeaker.
FIG. 4 illustrates another known telescopic telephone 400, which is, introduced in the Finnish registered design application No. 285/97. The telephone comprises a housing 401 and an upper sliding part 402 including a loudspeaker 403, a display 404 and a small part of the keys 405. The housing 401 includes the rest of the keys 406, a microphone 407 and an antenna 408. For transporting the telephone, the upper sliding part 402 can be sled on top of the housing 401, so that the keyboard 406 is covered. The functional practicality of this embodiment is dubious, because the antenna is easily left inside the user's hand, or very near to the user's hand, in which case it does not work in the best possible way. In order to realise a precise and versatile display in the embodiment of FIG. 4, there is needed a large amount of leads in between the housing and the upper sliding part, which is problematic with respect to the technical applications. Usually the display 404 is provided with a glass plate or other such easily breakable part that requires a solid supporting structure around it; this requirement is difficult to fulfil in the embodiment according to FIG. 4. Moreover, there are shortcomings in the user ergonomics.
FIGS. 5a and 5b illustrate a known method for realising a large-size user interface. A multiple-use mobile phone 500 comprises a top part 501 and a bottom part 502, which are interconnected with a hinge. The outer surface of the top part 501 constitutes a first user interface including a small-size display 503 and a number keyboard 504. The inner surfaces of the top part 501 and the bottom part 502 are shown by opening the telephone like a book, as is seen in FIG. 5b. The inner surfaces comprise another user interface provided with a large-size display and a letter keyboard 506. This application is not as such suited to the manufacturing of a mobile phone only, because in the position illustrated in FIG. 5b, the instrument 500 cannot be held on the side of the head like a telephone.